Rickover was promoted to vice admiral in 1958, the same year that he was awarded the first of two Congressional Gold Medals . [33] He exercised tight control for the next three decades over the ships, technology, and personnel of the nuclear Navy, interviewing and approving or denying every prospective officer being considered for a nuclear ship. Over the course of Rickover's career, these personal interviews numbered in the tens of thousands; over 14,000 interviews were with recent college-graduates alone. The interviewees ranged from midshipmen and newly commissioned ensigns destined for nuclear-powered submarines and surface combatants, to very senior combat-experienced Naval Aviator captains who sought command of nuclear-powered aircraft carriers. The content of most of these interviews has been lost to history, though some were later chronicled in several books on Rickover's career, as well as in a rare personal interview with Diane Sawyer in 1984. [34] [35] [36] [37] [38]